Boils and carbuncles are painful, pus-filled bumps caused by bacterial infection of hair follicles. Boils usually start as red lumps, while carbuncles are clusters of connected boils. They can occur in anyone but are more common in teenagers and young adults, as well as those with eczema, obesity, or a weak immune system. Symptoms include redness, swelling, tenderness, and formation of pus. Warm compresses and cleaning with antiseptic can help drainage and healing. Seeking medical care is advised if boils do not heal within a week or become very painful.